"""Implement these functions without changing the raw materials."""
def normalize(record, source):
    """Return a canonical event for source A/B; raise ValueError for invalid data."""
    raise NotImplementedError("Implement field mapping and UTC conversion")

def classify_order(order, events, cutoff):
    """Apply the cutoff and cancellation precedence before classifying an order."""
    raise NotImplementedError("Filter future events first")

def service_band(rate, n, rules):
    """Check sample size before the percentage-point thresholds."""
    raise NotImplementedError("Keep percentages and percentage points distinct")